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52 :: Computer and Office Applications
INTRODUCTION TO INTERNET
3.1 INTRODUCTION
In the present age of information Technology, use of Internet is becoming quite popular for accessing information on any topic of your interest. It also provides tremendous opportunities to students, researchers and professionals for getting information on matters related to academic and professional topics and lot more. In the present world, most of the people who have computers around themselves use Internet to access information from the World Wide Web, exchange messages & documents and e-services.
3.2 OBJECTIVES
After going through this lesson, you would be able to: explain various terminology used in internet use various services provided by internet search the desired information over internet define e-mail and its various features explain the process of downloading file.
3.3 INTERNET
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite (TCP/ IP) to serve billions of users worldwide. It is a network of networks that consists of millions of private, public, academic, business, and government networks, of local to global scope,
Introduction to Internet :: 53 that are linked by a broad array of electronic, wireless and optical networking technologies. The Internet carries a vast range of information resources and services, such as the inter- linked hypertext documents of the World Wide Web (WWW) and the infrastructure to support electronic mail.
3.3.1 Uses of Internet
Internet has been the most useful technology of the modern times which helps us not only in our daily lives, but also our personal and professional lives developments. The internet helps us achieve this in several different ways. For the students and educational purposes the internet is widely used to gather information so as to do the research or add to the knowledge of various subjects. Even the business professionals and the professionals like doctors, access the internet to filter the necessary information for their use. The internet is therefore the largest encyclopedia for everyone, in all age categories. The internet has served to be more useful in maintaining contacts with friends and relatives who live abroad permanently.
3.3.2 Advantages of Internet:
E-mail: Email is now an essential communication tools in business. With e-mail you can send and receive instant electronic messages, which works like writing letters. Your messages are delivered instantly to people anywhere in the world, unlike traditional mail that takes a lot of time. Email is free, fast and very cheap when compared to telephone, fax and postal services. 24 hours a day - 7 days a week : Internet is available, 24x7 days for usage. Information: Information is probably the biggest advantage internet is offering. There is a huge amount of information available on the internet for just about every subject, ranging from government law and services, trade fairs and conferences, market information, new ideas and technical support. You can almost find any type of data on almost any kind of subject that you are looking for by using search engines like google, yahoo, msn, etc.
Introduction to Internet :: 55 Internet addiction: There is some controversy over whether it is possible to actually be addicted to the Internet or not. Some researchers, claim that it is simply people trying to escape their problems in an online world. Children using the Internet has become a big concern. Most parents do not realize the dangers involved when their children log onto the Internet. When children talk to others online, they do not realize they could actually be talking to a harmful person. Moreover, pornography is also a very serious issue concerning the Internet, especially when it comes to young children. There are thousands of pornographic sites on the Internet that can be easily found and can be a detriment to letting children use the Internet. Virus threat: Today, not only are humans getting viruses, but computers are also. Computers are mainly getting these viruses from the Internet. Virus is is a program which disrupts the normal functioning of your computer systems. Computers attached to internet are more prone to virus attacks and they can end up into crashing your whole hard disk. Spamming: It is often viewed as the act of sending unsolicited email. This multiple or vast emailing is often compared to mass junk mailings. It needlessly obstruct the entire system. Most spam is commercial advertising, often for dubious products, get-rich-quick schemes, or quasi-legal services. Spam costs the sender very little to send — most of the costs are paid for by the recipient or the carriers rather than by the sender
3.4 SERVICES OF INTERNET -E-mail, FTP, Telnet
Email, discussion groups, long-distance computing, and file transfers are some of the important services provided by the Internet. Email is the fastest means of communication. With email one can also send software and certain forms of compressed digital image as an attachment. News groups or discussion groups facilitate Internet user to join for various kinds of debate, discussion and news sharing. Long-distance computing was an original inspiration for development of
56 :: Computer and Office Applications ARPANET and does still provide a very useful service on Internet. Programmers can maintain accounts on distant, powerful computers and execute programs. File transfer service allows Internet users to access remote machines and retrieve programs, data or text. (a) E-Mail (Electronic Mail) E-mail or Electronic mail is a paperless method of sending messages, notes or letters from one person to another or even many people at the same time via Internet. E-mail is very fast compared to the normal post. E-mail messages usually take only few seconds to arrive at their destination. One can send messages anytime of the day or night, and, it will get delivered immediately. You need not to wait for the post office to open and you don’t have to get worried about holidays. It works 24 hours a day and seven days a week. What’s more, the copy of the message you have sent will be available whenever you want to look at it even in the middle of the night. You have the privilege of sending something extra such as a file, graphics, images etc. along with your e-mail. The biggest advantage of using e- mail is that it is cheap, especially when sending messages to other states or countries and at the same time it can be delivered to a number of people around the world. It allows you to compose note, get the address of the recipient and send it. Once the mail is received and read, it can be forwarded or replied. One can even store it for later use, or delete. In e-mail even the sender can request for delivery receipt and read receipt from the recipient. (i) Features of E-mail: One-to-one or one-to-many communications Instant communications Physical presence of recipient is not required Most inexpensive mail services, 24-hours a day and seven days a week Encourages informal communications (ii) Components of an E-mail Address As in the case of normal mail system, e-mail is also based upon the concept of a recipient address. The email address
58 :: Computer and Office Applications Fig. 3. (ii) The basic steps in an FTP session Start up your FTP client, by typing ftp on your system’s command line/’C>’ prompt (or, if you are in a Windows, double-click on the FTP icon). Give the FTP client an address to connect. This is the FTP server address to which the FTP client will get connected Identify yourself to the FTP remote site by giving the Login Name Give the remote site a password Remote site will verify the Login Name/Password to allow the FTP client to access its files Look directory for files in FTP server Change Directories if requird Set the transfer mode (optional); Get the file(s) you want, and Quit. (c) Telnet (Remote Computing) Telnet or remote computing is telecommunication utility software, which uses available telecommunication facility and allows you to become a user on a remote computer. Once you SERVER A FTP Commands USER FTP Replies (^) A USER FILE SYSTEM SERVER B Connection (^) USER B FILE SYSTEM FTP SERVER CLIENT FTP USER INTERFACE
Introduction to Internet :: 59 gain access to remote computer, you can use it for the intended purpose. The TELNET works in a very step by step procedure. The commands typed on the client computer are sent to the local Internet Service Provider (ISP), and then from the ISP to the remote computer that you have gained access. Most of the ISP provides facility to TELENET into your own account from another city and check your e-mail while you are travelling or away on business. The following steps are required for a TELNET session Start up the TELNET program Give the TELNET program an address to connect (some really nifty TELNET packages allow you to combine steps 1 and 2 into one simple step) Make a note of what the “escape character” is Log in to the remote computer, Set the “terminal emulation” Play around on the remote computer, and Quit. 3.5 TYPES OF INTERNET CONNECTIONS There are five types of internet connections which are as follows: (i) Dial up Connection (ii) Leased Connection (iii) DSL connection (iv) Cable Modem Connection (v) VSAT 3.5.1 Dial up connection Dial-up refers to an Internet connection that is established using a modem. The modem connects the computer to standard phone lines, which serve as the data transfer medium. When a user initiates a dial-up connection, the modem dials a phone number of an Internet Service Provider (ISP) that is designated to receive dial-up calls. The ISP then establishes the connection, which usually takes about ten seconds and is accompanied by several beepings and a buzzing sound.
Introduction to Internet :: 61 Advantage Secure and private: dedicated exclusively to the customer Speed: symmetrical and direct Reliable: minimum down time Wide choice of speeds: bandwidth on demand, easily upgradeable Leased lines are suitable for in-house office web hosting Disadvantages Leased lines can be expensive to install and rent. Not suitable for single or home workers Lead times can be as long as 65 working days Distance dependent to nearest POP Leased lines have traditionally been the more expensive access option. A Service Level Agreement (SLA) confirms an ISP’s contractual requirement in ensuring the service is maintained. This is often lacking in cheaper alternatives. 3.5.3 DSL connection Digital Subscriber Line ( DSL ) is a family of technologies that provides digital data transmission over the wires of a local telephone network. DSL originally stood for digital subscriber loop. In telecommunications marketing, the term DSL is widely understood to mean Asymmetric Digital Subscriber Line (ADSL), the most commonly installed DSL technology. DSL service is delivered simultaneously with wired telephone service on the same telephone line. This is possible because DSL uses higher frequency bands for data separated by filtering. On the customer premises, a DSL filter on each outlet removes the high frequency interference, to enable simultaneous use of the telephone and data. The data bit rate of consumer DSL services typically ranges from 256 kbit/s to 40 Mbit/s in the direction to the customer (downstream), depending on DSL technology, line conditions, and service-level implementation. In ADSL, the data throughput
62 :: Computer and Office Applications in the upstream direction, (the direction to the service provider) is lower, hence the designation of asymmetric service. In Symmetric Digital Subscriber Line (SDSL) services, the downstream and upstream data rates are equal. Advantages: Security: Unlike cable modems, each subscriber can be configured so that it will not be on the same network. In some cable modem networks, other computers on the cable modem network are left visibly vulnerable and are easily susceptible to break in as well as data destruction. Integration: DSL will easily interface with ATM and WAN technology. High bandwidth Cheap line charges from the phone company. Good for “bursty” traffic patterns Disadvantages No current standardization: A person moving from one area to another might find that their DSL modem is just another paperweight. Customers may have to buy new equipment to simply change ISPs. Expensive: Most customers are not willing to spend more than $20 to $25 per month for Internet access. Current installation costs, including the modem, can be as high as $750. Prices should come down within 1-3 years. As with all computer technology, being first usually means an emptier wallet. Distance Dependence: The farther you live from the DSLAM (DSL Access Multiplexer), the lower the data rate. The longest run lengths are 18,000 feet, or a little over 3 miles. 3.5.4 Cable Modem Connection A cable modem is a type of Network Bridge and modem that provides bi-directional data communication via radio frequency channels on a HFC and RFoG infrastructure. Cable modems
64 :: Computer and Office Applications digital packets, meaning they provide high-speed Internet access. This makes cable modem connections much faster than traditional dial-up connections. Bandwidth: Cable modems have the potential to receive data from their cable provider at speeds greater than 30 megabits per second; unfortunately, this speed is rarely ever realized. Cable lines are shared by all of the cable modem users in a given area; thus, the connection speed varies depending upon the number of other people using the Internet and the amount of data they are receiving or transmitting. File Transfer Capabilities: Downloads may be faster, but uploads are typically slower. Since the same lines are used to transmit data to and from the modem, priority is often given to data traveling in one direction. Signal Integrity: Cable Internet can be transmitted long distances with little signal degradation. This means the quality of the Internet signal is not significantly decreased by the distance of the modem from the cable provider. Routing: Cable routers allow multiple computers to be hooked up to one cable modem, allowing several devices to be directly connected through a single modem. Wireless routers can also be attached to your cable modem. Rely on Existing Connections: Cable modems connect directly to preinstalled cable lines. This is advantageous because you do not need to have other services, such as telephone or Internet, in order to receive Internet through your cable modem. The disadvantage is that you cannot have cable internet in areas where there are no cable lines. Disadvantages Cable internet technology excels at maintaining signal strength over distance. Once it is delivered to a region, however, such as a neighborhood, it is split among that regions subscribers. While increased capacity has diminished the effect somewhat, it is still possible that users will see significantly lower speeds at peak times when more people are using the shared connection.
Introduction to Internet :: 65 Bandwidth equals money, so cable’s advantage in throughput comes with a price. Even in plans of similar speeds compared with DSL, customers spend more per Mb with cable than they do with DSL. It’s hard to imagine, but there are still pockets of the United States without adequate cable television service. There are far fewer such pockets without residential land-line service meaning cable internet is on balance less accessible in remote areas. 3.5.5 VSAT Short for very small aperture terminal, an earthbound station used in satellite communications of data, voice and video signals, excluding broadcast television. A VSAT consists of two parts, a transceiver that is placed outdoors in direct line of sight to the satellite and a device that is placed indoors to interface the transceiver with the end user’s communications device, such as a PC. The transceiver receives or sends a signal to a satellite transponder in the sky. The satellite sends and receives signals from a ground station computer that acts as a hub for the system. Each end user is interconnected with the hub station via the satellite, forming a star topology. The hub controls the entire operation of the network. For one end user to communicate with another, each transmission has to first go to the hub station that then retransmits it via the satellite to the other end user’s VSAT. Advantages Satellite communication systems have some advantages that can be exploited for the provision of connectivity. These are: Costs Insensitive to Distance Single Platform service delivery (one-stop-shop) Flexibility Upgradeable Low incremental costs per unit Disadvantages However like all systems there are disadvantages also. Some of these are
Introduction to Internet :: 67
- You will then be asked to select the folder where you want to save the program or file, using a standard “Save As” dialog box. Pay attention to which folder you select before clicking the “Save” button. It may help you to create a folder like “C:\Download” for all of your downloads, but you can use any folder you’d like.
- The download will now begin. Your web browser will keep you updated on the progress of the download by showing a progress bar that fills up as you download. You will also be reminded where you’re saving the file. The file will be saved as “C:\Download\dweepsetup.exe” in the picture below. (Fig. 3.3(b)) Note: You may also see a check box labeled “Close this dialog box when download completes.” If you see this check box, it helps to uncheck this box. You don’t have to, but if you do, it will be easier to find the file after you download it.
- Depending on which file you’re downloading and how fast your connection is, it may take anywhere from a few seconds to a few minutes to download. When your download is finished, if you left the “Close this dialog box when download completes” option unchecked, you’ll see a dialog box as shown in fig. 3.3(c) : Fig 3.3.(a) Downloading Window Fig 3.3.(b) Downloading Window Fig 3.3.(c) Downloading Window
68 :: Computer and Office Applications
- Now click the “Open” button to run the file you just downloaded. If you don’t see the “Download complete” dialog box, open the folder where you saved the file and double-click on the icon for the file there. What happens next will depend on the type of file you downloaded. The files you’ll download most often will end in one of two extensions. (An extension is the last few letters of the filename, after the period.) They are: o .EXE files: The file you downloaded is a program. Follow the on-screen instructions from there to install the program to your computer and to learn how to run the program after it’s installed. o .ZIP files: ZIP is a common file format used to compress and combine files to make them download more quickly. Some versions of Windows (XP and sometimes ME) can read ZIP files without extra software. Otherwise, you will need an unzipping program to read these ZIP files. Common unzipping programs are WinZip, PKZIP, and Bit Zipper, but there are also many others. Many unzipping programs are shareware, which means you will need to purchase them if you use them beyond their specified trial period. INTEXT QUESTION 3.
- What are the different types of Internet Connection?
- Fill in the blanks: (a) A __________ is a type of Network Bridge and modem that provides bi-directional data communication via radio frequency channels on a HFC and RFoG infrastructure. (b) The ________ is a global system of interconnected computer networks that use the standard Internet protocol suite (TCP/IP) to serve billions of users worldwide. (c) VoIP stands for______________ , referring to the protocol that underlies all Internet communication.
